/**
 * Two pass Gaussian blur filter (horizontal and vertical blur shaders)
 * - described in http://www.gamerendering.com/2008/10/11/gaussian-blur-filter-shader/
 *   and used in http://www.cake23.de/traveling-wavefronts-lit-up.html
 *
 * - 9 samples per pass
 * - standard deviation 2.7
 * - "h" and "v" parameters should be set to "1 / width" and "1 / height"
 */

Map<String, dynamic> HorizontalBlurShader = {
  "uniforms": {
    'tDiffuse': {},
    'h': {"value": 1.0 / 512.0}
  },
  "vertexShader": [
    'varying vec2 vUv;',
    'void main() {',
    '	vUv = uv;',
    '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',
    '}'
  ].join('\n'),
  "fragmentShader": [
    'uniform sampler2D tDiffuse;',
    'uniform float h;',
    'varying vec2 vUv;',
    'void main() {',
    '	vec4 sum = vec4( 0.0 );',
    '	sum += texture2D( tDiffuse, vec2( vUv.x - 4.0 * h, vUv.y ) ) * 0.051;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x - 3.0 * h, vUv.y ) ) * 0.0918;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x - 2.0 * h, vUv.y ) ) * 0.12245;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x - 1.0 * h, vUv.y ) ) * 0.1531;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y ) ) * 0.1633;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x + 1.0 * h, vUv.y ) ) * 0.1531;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x + 2.0 * h, vUv.y ) ) * 0.12245;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x + 3.0 * h, vUv.y ) ) * 0.0918;',
    '	sum += texture2D( tDiffuse, vec2( vUv.x + 4.0 * h, vUv.y ) ) * 0.051;',
    '	gl_FragColor = sum;',
    '}'
  ].join('\n')
};
